Mass balance analysis of algal biodiesel reports on a recent paper in which the authors analyze the sustainability of algal biodiesel from a mass balance perspective. The paper, Bioresource Tech. 102, 1185, essentially highlights one of the tradeoffs with algal biodiesel. The low tech route of large containment ponds limits the total output of dry biomass per hectare, as evidenced by the author’s computation that even 11 square miles of algae ponds, at a growth rate of 50 g of bone-dry biomass per square meter per day, would only be sufficient to replace 0.1% of the US consumption of diesel.

Of course, there are many ways to increase the output per hectare. One of these are vertical tubes, or bioreactors, for algae growth. The issue with this approach is that it is capital intensive, requiring not only the tubes, but cooling systems to prevent algae death from overheating and requires higher overhead, since the tubes must be scrubbed occasionally to reduce fouling.

If I were to be looking at this area for technology breakthroughs, I’d be looking at people applying anti-fouling or other surface chemistry applications to reduce the maintenance costs, or clever engineers designing passive cooling systems for these reactors. I can imagine a system where the bioreactors were built to exchange heat with an HVAC system in cooler environments, or with their own ground-sourced heat pump in warmer times. The cost of the cooling is a major barrier and it would be a win to spread that cost around amongst several different systems.


Robert Rapier at the R-squared Energy Blog has written a very good analysis of how ethanol may be more efficient a transport fuel than gasoline, despite the fact that ethanol contains fewer BTUs per gallon than gasoline. The upshot of it is that because of ethanol’s incredibly high octane rating (over 100!), it is possible to run an engine on ethanol at a much higher compression ratio than one could with gasoline. This would allow you to extract more work from the ethanol than can be extracted from the gasoline.

(note: Robert works for Accoya, one of the most interesting green materials companies out there. I currently have a sample of their product and if I order from them for a project I’m working on, I’ll blog about it here.)

More on the biofuel controversy

I posted an article earlier critiquing the media reaction to the recent reports on biofuels and land use management. Worldchanging has just posted a similar, fairly in-depth, critique as well. Their analysis goes more in depth into the specifics of each report, so I highly recommend it. What they do point out is that the Science articles are nuanced and that it was clear that the media in general either missed the nuance or ignored it.

Craig Venter wants to save the world

No one grandstands quite like Craig Venter. Whether its leading a team racing the government to the first human genome sequenced, succeeding, or admitting that his team beat the government by sequencing his own genome, this guy has style like few others in science. And while physicists at least have the reputation of having large egos installed as part of their graduate training, Venter’s ego is apparently physicist-sized, at least according to Wired and Forbes.

That being said, there is something phenomenally inspiring about the folks who have no shame about tackling the really big problems. This is a constructive sort of hubris, the kind that Larry Wall correctly identified as a virtue. Venter’s glorious hubris was on display this week at the TED conference, where he announced that he was working on a project to engineer a bacteria that turns carbon dioxide into methane and octane and that he expects results within 18 months on these fourth generation fuels.

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More on biofuels vs. greenhouse gases

In regards to my previous post on the recent studies on biofuels, WorldChanging has posted an article about the issue, citing a study released by the Sierra Club as well as the Science report. The WorldChanging blog post mentions that the Science report “reinforced the urgency of moving to second-generation biofuels.”

In considering this topic, I think something else extremely valuable is coming out of the biofuel boom. We’re learning how to quickly estimate environmental costs.

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Does the blame fall on biofuels

In the alternative energy circles, a recent Science magazine online article published by a group from Minnesota has been making a lot of waves in the media. This article from the Seattle Times is typical of the coverage. There are a couple of issues with both the article and the coverage of the article that I’d to point out.

First, let me tackle the article. While no one will argue that corn ethanol is an extremely poor choice for a biofuel feedstock, it is also inarguable that the article focused on current biofuel technology. This implicitly assumes that all new biofuels will be roughly equally bad for the environment. Clearly, this is not the case, since algal-derived biodiesel and similar biomass-derived fuels will not contribute equally to global warming through the destruction of ecosystems. The article also assumed by implication that biofuels are the primary driver behind conversion of ecosystems to cropland. Past data would indicate that this is almost certainly not the case, since slash-and-burn was prevalent in the Amazon basin well before biofuels become a cause celebre. The issues around land use in the developing world would exist with or without biofuels contributing, since there is rarely an incentive for the governments who control these lands to preserve them. Rain forests do not yield significant economic benefit to those who live near them. All the biofuel boom has done is exacerbate the situation. Hopefully, this will bring attention to dealing with the root causes of the destruction of these ecosystems – namely, food security and poverty.

The media has been largely guilty of indulging in shrill hachet jobs on the nascent biofuel industry based on this article. I am certainly not implying that the authors of the Science report intended this; rather, I think that the natural tendency to want to take potshots at large targets is to blame here. Nevertheless, I think its important that people interested in short term energy development continue to work on capturing energy from biomass. With any luck, we’ll solve both the petroleum problem and the disappearing ecosystems problem at the same time.